CT machine is a computerized x-ray tomography machine, it is the use of X-rays on a selected part of the human body to scan a certain thickness of the layer, by the detector to accept the attenuation value of the layer of X-rays and converted into current, and then by the analog converter into the required digital, by the electronic computer processing arranged into a digital matrix. The digital matrix is then converted into a matrix of pixels of different shades of gray by a digital/analog converter and displayed on a television screen, which is then photographed by a camera to make a film, which is a conventional CT scan. The black area of the film indicates the low absorption area, i.e., the low density area, and the white area indicates the high absorption area, i.e., the high density area, and the different density values are measured as different CT values.
It was developed from the X-ray machine. Its resolution and qualitative diagnostic accuracy is much higher than the general X-ray machine.
Generally speaking, CT can be used to examine all organic diseases, especially organic space-occupying lesions with large differences in density, which can be examined and qualitatively diagnosed. However, the most suitable CT examination of the disease is brain disease, which is the best for tumor, hemorrhage and infarction, followed by abdominal parenchymal organs occupational lesions, such as liver, spleen, pancreas, kidney, prostate and other parts of the tumor, breast, thyroid and other parts of the mass can also be displayed and make a diagnosis; and then the next is the thorax, lungs, the cardiac cavity of the mass, the spine, the spinal cord, the pelvis, the gallbladder, the uterus, and other parts of the mass examination. CT has a slightly worse effect on some diffuse inflammation and degenerative lesions, such as hepatitis, CT examination has little value, the examination of gastrointestinal lesions, CT is not as good as endoscopy.
CT is easy to detect tumors, masses, bleeding, etc.; but the lesions are too small, especially those less than 6 mm, CT is difficult to detect.